Inflammation during obesity is not all bad: evidence from animal and human studies

Abstract

Chronic inflammation is a characteristic of obesity and is associated with accompanying insulin resistance, a hallmark of type 2 diabetes mellitus (T2DM). Although proinflammatory cytokines are known for their detrimental effects on adipose tissue function and insulin sensitivity, their beneficial effects in the regulation of metabolism have not drawn sufficient attention. In obesity, inflammation is initiated by a local hypoxia to augment angiogenesis and improve adipose tissue blood supply. A growing body of evidence suggests that macrophages and proinflammatory cytokines are essential for adipose remodeling and adipocyte differentiation. Phenotypes of multiple lines of transgenic mice consistently suggest that proinflammatory cytokines increase energy expenditure and act to prevent obesity. Removal of proinflammatory cytokines by gene knockout decreases energy expenditure and induces adult-onset obesity. In contrast, elevation of proinflammatory cytokines augments energy expenditure and decreases the risk for obesity. Anti-inflammatory therapies have been tested in more than a dozen clinical trials to improve insulin sensitivity and glucose homeostasis in patients with T2DM, and the results are not encouraging. One possible explanation is that anti-inflammatory therapies also attenuate the beneficial effects of inflammation in stimulating energy expenditure, which may have limited the efficacy of the treatment by promoting energy accumulation. Thus, the positive effects of proinflammatory events should be considered in evaluating the impact of inflammation in obesity and type 2 diabetes.

Effect of anti-gut inflammatory agent on insulin resistance and lipid profile of mice fed different diets

“…Moreover, anti-inflammation may lead to serious side effects. Indeed, studies from animal and human suggest inflammation in obesity is not always deleterious, while results from many studies are controversial [6].…”

“…Therefore, antiinflammatory scheme becomes as new treatments for metabolic disorders [4]. Although many preclinical studies support this opinor, results generated from clinical trials are quite controversial and still ongoing [5,6].…”

Obesity Induced Inflammation – A Complex Condition

“…This is a great disappointment that these interventions could not remarkably improve the major inflammation associated disorders including glucose homeostasis. 9 To interpret the results it is required to respond to this basic challenging question that whether there is any benefit of suppressing metaflammation. In fact, despite the destructive effects of inflammation on insulin resistance and the metabolism of fat tissue, there may be potential benefits of inflammation in obesity, which has not been considered enough.…”

“…In fact, despite the destructive effects of inflammation on insulin resistance and the metabolism of fat tissue, there may be potential benefits of inflammation in obesity, which has not been considered enough. Expanding evidence propose the essential role of proinflammatory cells and mediators in providing sufficient blood flow of adipose tissue through angiogenesis, regulation of metabolism, adipose tissue remodeling, and adipocyte differentiation, 9 however, these beneficial effects are the matter of discussion.…”

“…9 The proinflammatory factor IL-15 might be an example of the positive function of inflammation in obesity. According to recent studies, IL-15 lessens weight gain and lipogenesis probably by enhancing energy expenditure and activating brown fat.…”